Larson, Larsson, Larsen are last names showing that you have Scandinavian ancestry, and that you in your paternal line have someone called Lars! Lars is a common first (given) name in the three Scandinavian countries. The name Larson (with variants) has only been in use as last name since around 1850, thus not being suitable for Y-DNA surname research. Scandinavians with last name Larsson are not related or descendants from the same family, instead it means that they had an ancestor whose given name was Lars, and that the family started to use the patronymic Larsen as a new hereditary last name, sometime around 1800-1900 or on emigration to America.

A patronymic chosen as family name is called a frozen patronymic.

The -sen versions are mainly Danish or Norwegian, the -son versions are Swedish or Norwegian.

The use of frozen patronymic names as family names only go back 2-6 generations from people today. This is not enough to use it as for Y-DNA surname research, which relies on the principle that surnames are inherited unchanged from father to son through the centuries (just like the Y-chromosome). For Frozen patronymic names this is not the case.

People with patronymic last names from Denmark, Norway or Sweden should join the geographical projects for the area.

If country of origin is known, please join one of these projects - and note that the project admins will assist in adding you to the most relevant ones:

A patronymic name (pater=father, latin) is a name constructed from the father’s given name. In Norse custom patronyms and matronyms were formed by using the ending -son (later -søn and -sen in Danish and Norwegian) to indicate “son of”, and -dóttir (Icelandic -dóttir, Swedish and Norwegian -dotter, Danish and Norwegian -datter) for “daughter of”. This name was used as a descriptive name for most Scandinavians. Sometimes also a third name based on location or personal characteristic was added to differentiate people.

The patronymic system gradually disappeared and was replaced with a last name system in all three Scandinavian countries:

Denmark during 1828-1904

Sweden around 1900

Norway in 1923

Families would then adopt a name, either a patronymic in recent use, a farm name (Norway) or place name from the family history, a soldier name (Sweden) or other to be their hereditary last name.

Patronymic: a descriptive name telling us the first name of the person’s father

Surname: a hereditary last name normally inherited from one’s father, that can be used to follow a paternal line back in time, shared by the whole family

Last name: a last name is used by an individual and his/her family, normally inherited from one of the parents. A last name can be a hereditary surname, a former farm name, a frozen patronymic or other variants, and was introduced in Denmark from 1828, in Sweden from 1850 and in Norway in 1923.

Frozen Patronymic: A former patronymic (male form, -sen or -son) adopted by a family as their new last name, family name. It is not considered a surname.

A Surname project for Y-DNA is not useful for these Scandinavian Frozen Patronymic Last Names.

We therefore assist our members in rather joining the geographical projects and haplogroup projects for their results.
This project is mainly a Portal to DNA-testing for people who are not sure which project to join.

Scandinavia and the Nordic Countries

Scandinavia = Denmark + Norway + Sweden

Nordic countries = Scandinavia + Finland + Iceland

In Iceland the patronymic names are still used, and people do not have hereditary surnames.

Finland is one of the Nordic countries together with the Scandinavian countries, but it is not part of Scandinavia, and has a very different language as well as a naming tradition. In Finland hereditary surnames have been used for many centuries.